Cooperative nucleophilic–electrophilic organocatalysis by ionic liquids

Abstract

The anionic and the cationic partners of ionic liquids may act cooperatively and independently as nucleophilic and electrophilic catalysts. This ambiphilic propensity was demonstrated by kinetically discriminating the contributions of the anion (nucleophilic catalyst) and of the cation (electrophilic catalyst) to the solvent-free Baylis-Hillman dimerization of cyclohexenone catalysed by ionic liquids.

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

“…Regardless of its nature, the cation might also activate DMC towards nucleophilic addition: a cooperative nucleophilic–electrophilic mechanism could therefore operate (Scheme 11) [63]. …”

Methyltriphenylphosphonium Methylcarbonate, an All‐In‐One Wittig Vinylation Reagent

“…Likewise, other direct procedurestoconvert ac arbonyl into am ethylene group involve complex and expensive reagents such as Te bbe's complex, whichisw ater-and air-sensitive. [20] Considering the structures of these methyl-phosphonium compounds from ad ifferent perspective (Scheme 1, left box) [18] suggestst hat they incorporate both the basic and phosphonium moieties indispensable for the preparation of phosphorous ylides.W et herefore imagined that the methylcarbonate anion might be able to generate the ylide in situ, as shown in Scheme1,a nd thus give access to an ew Wittig vinylation protocol. [18] The resulting compounds have the structure [R 3 QCH 3 ] [CH 3 OCO 2 ]( Q= N, P) and behave as very efficient basic organocatalysts.…”

“…[19] This catalytic behaviorw as explained by acooperative double activation mechanism of the substrate. [20] Considering the structures of these methyl-phosphonium compounds from ad ifferent perspective (Scheme 1, left box) [18] suggestst hat they incorporate both the basic and phosphonium moieties indispensable for the preparation of phosphorous ylides.W et herefore imagined that the methylcarbonate anion might be able to generate the ylide in situ, as shown in Scheme1,a nd thus give access to an ew Wittig vinylation protocol.…”

Facile construction of 3-indolochromenes and 3-indoloxanthenes via EDDF catalyzed one-pot three component reactions

“…[35][36][37][38] EDDF is a salt and hence, on similar lines, it can act as an ambiphilic catalyst 29 wherein both the cation and anion act cooperatively as an electrophile and nucleophile. Recently, an ambiphilic dual activation role has been suggested for various catalysts including ionic liquids.…”